1. Field of Invention
The present invention relates to the field of fuel tank re-fueling devices. More particularly, the present invention relates to a device for prevention of fuel over-filling during re-fueling of a fuel tank. More particular yet, the present invention involves a fuel overflow prevention system particularly useful in a marine environment, where the system includes an optional audible signal to indicate fuel flow and level, and sealing features that account for expansion of fuel within the tank and to prevent fuel spillage.
2. Description of Prior Art
For as long as there have been fuel tanks and devices to refill them, there has been fuel spillage. Some contemporary estimates of fuel spillage are in excess of six million gallons annually in the United States alone. Globally, fuel spillage is many times this amount. The resultant fuel losses are economically and environmentally detrimental in terms of the wasted fuel resources and environmental contamination. Accordingly, numerous devices have been developed to prevent or otherwise limit fuel spillage during refueling. Known fuel containers that utilize such devices commonly include an intake, a fuel tank, and a vent. Typically, these devices are located in or around the intake and/or the vent.
In the field of fuel overflow prevention devices, there have been attempts to provide warning signals that indicate overflow conditions. It is to be noted at the outset, however, that these devices fail to account for expansion of the fuel within the tank. Nevertheless, while many fuel tanks have little in the way of a means for signaling that a tank is deemed to be effectively full, devices have been developed for that purpose. In general, there are two categories of such signaling devices. One category includes devices which are activated upon the fuel tank being filled reaching its defined full capacity, such devices typically being in the form of an audible alarm. The other category includes devices that disengage, or otherwise negate some constant signal, when the tank reaches a defined full fuel capacity. Such "negative" notification typically is in the form of an audible signal that is present during fueling but ceases when the tank is at or near full capacity.
The first category of overflow signaling devices having a signal activated only when the tank is full typically involves complexity are so complex that whatever advantages might otherwise be offered are undercut. Indeed, elaborate electronic sensing and signals have been developed with increased expense and complexity. Sensors in such devices are exposed to a variety of temperatures and petroleum distillates that may degrade the reliability of sensor components. The most serious aspect of this reliability problem in such prior-art devices is that sensor failure will not become apparent in the re-fueling process until after the tank has been overfilled and spillage has occurred. "Negative" activation alleviates much of this problem.
The second category of signaling devices utilizes "negative" activation by providing a constant signal during the fueling process that stops only when the tank is full. Although anyone using such a signaling device would readily notice if the device fails to produce the constant signal, other problems arise with such a device. Most commonly, a user will leave a fuel pump unattended during the re-fueling process. If the signal is an audible one, as it typically is, the user may be lulled into a false sense of control over the pump. When such a signal ceases, indicating that the tank is full, the user may then be unable to quickly access the pump so as to manually prevent overflow. Further, prior-art devices fail to substantially allow for thermal expansion of the fuel that can result in a full tank becoming "over-full" as the temperature rises. This can create a siphoning effect and a continuous fuel spill through the tank vent. One needs, therefore, to avoid filling the tank all the way.
Other related prior-art fuel overflow indicators have their own disadvantages. One prior-art re-fueling device is that of Delisle, Jr. et al. (U.S. Pat. No. 5,023,608) which involves a fuel filler alarm including a whistle and overflow reservoir combination that is attached to the vent hole of a fuel tank on a boat. The whistle in the Delisle device is designed to maintain an audible sound while fuel is being pumped into the fuel tank. When the fuel tank reaches its capacity, the whistle stops and, ideally, a fuel attendant will shut off the fuel pump. The device of Delisle does allow for some error by the fuel attendant such that excess fuel may be stored in the overflow reservoir; however, this is only a stop-gap measure that likely works only in situations where a relatively small amount of spilled fuel is involved. If a distracted fuel attendant were drawn away from the fuel pump for some extended period of time, fuel would certainly spill from an overfilled overflow reservoir. In addition, such a design is intended to allow the tank to be completely filled. Accordingly, Delisle fails to provide any gap in the tank for fuel expansion subsequent to being filled.
Other such prior-art re-fueling devices exist that are deficient for similar reasons. A general defect in the prior-art is that there are no re-fueling systems that allow for thermal expansion subsequent to re-fueling while providing adequate signaling of proper fueling. It is well known to those skilled in the art of fuel production that fuel can expand by several percent over a temperature range of between about 60 and about 212 degrees Fahrenheit--a range typically experienced by gasoline transferred from an underground storage tank to a boat's fuel tank during a hot summer day. Further, facilitation of the standard automatic-shutoff features of most fuel pumps by pressure-creating devices is absent in the prior-art. This type of fuel pump is widely used throughout the retail gasoline market and operates generally by mechanically sensing the change in pressure in a fuel pump's nozzle to automatically stop fuel flow when the fuel reaches the nozzle. Two representative prior-art devices are those of Schupp (U.S. Pat. No. 5,181,022) and Langlois (U.S. Pat. No. 5,515,891).
Schupp includes a reservoir housing similar to Delisle but one having electronic sensors that signal an overfilled condition, rather than a constant signal that ceases upon a full-tank condition. This design of Schupp fails to provide for electronic failure caused by exposure of electronics sensitive to corrosive fuels and/or fuel additives. As well, the Schupp device may be susceptible to false sensing caused by fumes or small amounts of fuel splashed around the sensor that erroneously indicates the fuel has reached the capacity of the tank. Such problems may result in excessive overflow or even a boater's reliance on an erroneous indication that the tank is full. Similarly, Langlois includes primary and secondary fuel tanks and a full condition alarm that act in a fashion much like Schupp and Delisle. Langlois exhibits several flaws, including, most importantly, a lack of any sealing features that would create pressure sufficient to activate automatic-shut-off fuel pumps.
It is to be noted that there are feedback system available in fuel pumping systems, such as the Perko.TM. fill and vent unit for a fuel inlet with feedback tube. This arrangement has some advantages in regard to formation of an automatic shutoff fuel nozzle; however, the fuel return tube does not prevent unintended overflow that may be caused by expansion of the fuel within the tank. It would therefore be advantageous to have a fuel overflow prevention system that may be coupled to a fuel return line used in conjunction with an automatic shutoff device.
Accordingly, the prior art fails to provide any fuel overflow prevention device that provides "negative" notification with reliable control of fuel flow. Therefore, what is needed is a fuel overflow prevention device that provides signaling during re-fueling that ceases when the tank is just below its capacity, thereby indicating that fuel pumping should be turned off. What is also needed is such a device that provides automatic shut-off features for instances when fuel pumping is not manually turned off. Further, what is needed is such a device that ensures activation of standardized pressure-sensitive-pump-shut-off-triggers by providing a substantially sealed arrangement. Still further, what is needed is such a device that prevents fuel spillage that occurs due to thermal expansion of fuel. Yet further, what is needed is such a device that is relatively simple and not reliant upon electronics that may cause complete system failure with the failure of a relatively minor component.